System and method of routing telephone calls

ABSTRACT

A method of routing telephone calls is disclosed that includes receiving Voice over Internet Protocol (VoIP) packets at an integrated access device (IAD) from a VoIP remote worker feature server. The IAD communicates with a first private branch exchange (PBX) located at a first location. The VoIP packets are related to a VoIP call intended for a telephone number assigned by a second PBX at a second location.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. patent application Ser. No.10/947,050 filed Sep. 22, 2004, entitled “REMOTE WORKER ACCESS ONNETWORKED PBX SYSTEMS USING A VoIP PLATFORM,” the contents of which areincorporated by reference in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to routing telephone calls.

BACKGROUND

U.S. Pat. No. 5,247,571 to Kay et al. discloses an area-wide Centrexservice. Among the features provided by the area-wide Centrex service isan extension dialing feature. The extension dialing feature allows amulti-location customer to provide a specialized, abbreviated dialingplan for calls between multiple locations. Using this feature, anarea-wide Centrex station user can call any other station in thearea-wide Centrex network using the specialized dialing plan. Thisfeature offers multi-location Centrex customers a uniform abbreviateddialing plan between their PBX locations, Centrex locations, ISDN lines,and residential lines for people working from home.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is pointed out with particularity in the appendedclaims. However, other features are described in the following detaileddescription in conjunction with the accompanying drawing in which:

FIG. 1 is a block diagram of an embodiment of a system to provide remoteworker access on networked PBX systems over a VoIP platform;

FIG. 2 is a flow chart of an embodiment of a method of providingincoming calls to a remote worker; and

FIG. 3 is a flow chart of an embodiment of a method of providingoutgoing calls placed by the remote worker.

DETAILED DESCRIPTION OF THE DRAWINGS

A method of routing telephone calls is disclosed that includes receivingVoice over Internet Protocol (VoIP) packets at an integrated accessdevice (IAD) from a VoIP remote worker feature server. The IADcommunicates with a first private branch exchange (PBX) located at afirst location. The VoIP packets are related to a VoIP call intended fora telephone number assigned by a second PBX at a second location.

In another embodiment, a system to route telephone calls is disclosedthat includes a Voice over Internet Protocol (VoIP) remote workerfeature server. The VoIP remote worker feature server is configured toreceive an instruction from an administrator to route VoIP callsintended for a telephone number to a first public branch exchange (PBX).The telephone number is assigned by a second PBX. The VoIP remote workerfeature server is also configured to receive a VoIP call intended forthe telephone number from a second integrated access device (IAD)communicating with the second PBX. Further, the VoIP remote workerfeature server is configured to route the VoIP call to a first IADcommunicating with the first PBX.

In another embodiment, a method is disclosed that includes building atelephone number at a first public branch exchange (PBX). The telephonenumber is assigned by a second PBX. The method also includes receiving acall placed to the telephone number at the first PBX from a server.

FIG. 1 is a block diagram of an embodiment of a system to provide remoteworker access on networked PBX systems over a VoIP platform. In general,the system can be used to provide the remote worker feature between anynumber of PBXs, each of which serving a different customer location.However, for purposes of illustration and example, the system isdescribed with reference to a PBX 10 at a customer location 12, a PBX 14provided to a customer location 16, and a VoIP customer local areanetwork (LAN), such as a Hosted IP Communication Service (HIPCS) LAN 20,at a customer location 22.

An access point to a VoIP provider's IP network 24 is placed at each ofthe PBXs. The access points enable the various PBXs to communicate andinterwork with each other over the VoIP provider's IP network 24. TheVoIP provider further may permit the PBXs to interwork with theirVoIP-served locations (e.g. the customer location 22), as well as placecalls to other destinations via the IP network 24.

In one embodiment, an Integrated Access Device (IAD) is deployed as aCustomer-Provided Equipment (CPE) endpoint on each of the PBXs. Each IADserves as a customer-provided media gateway that converts analogtime-division multiplexed (TDM) voice traffic into IP packetized voice(e.g. VoIP) signals, and vice-versa. With reference to the example inFIG. 1, an IAD 26 is deployed at the customer location 12 to serve thePBX 10, and an IAD 30 is deployed at the customer location 16 to servethe PBX 14.

As illustrated in FIG. 1, the PBX 10 may interface to the IAD 26 by aPrimary Rate Interface (PRI) 32. Alternatively, the interface of the PBX10 to the IAD 26 may comprise stations of the PBX 10 since the PBX 10 isunder full customer control. Similarly, the PBX 14 may interface to theIAD 30 by a PRI 34. Alternatively, the interface of the PBX 14 to theIAD 30 may comprise stations of the PBX 14 since the PBX 14 is underfull customer control.

The IP network 24 managed by the VoIP provider interfaces to the IADsover an Internet access facility such as Dedicated Internet Access(DIA), for example. In the example of FIG. 1, the IAD 26 interfaces tothe IP network 24 over a DIA 36 or an alternative Internet accessfacility to provide access to the IP network 24 by the PBX 10. The IAD30 interfaces to the IP network 24 over a DIA 40 or an alternativeInternet access facility to provide access to the IP network 24 by thePBX 14. The VoIP customer LAN 20 at the customer location 22 interfaces,without an IAD, to the IP network 24 over a DIA 42 or an alternativeInternet access facility.

The IAD 26 converts traditional outgoing voice signals of the PBX 10into VoIP packets, and delivers the packets to the VoIP provider's IPnetwork 24 over the DIA 36 or alternative Internet access facility.Similarly, the IAD 30 converts traditional outgoing voice signals of thePBX into VoIP packets, and delivers the packets to the VoIP provider'sIP network 24 over the DIA 40 or alternative Internet access facility.

For incoming VoIP signals to the PBX 10, the IAD 26 receives VoIPpackets over the DIA 36 or alternative Internet access facility,converts the VoIP packets into a traditional voice call signal, anddelivers the signal to the PBX 10. Similarly, for incoming VoIP signalsto the PBX 14, the IAD 30 receives VoIP packets over the DIA 40 oralternative Internet access facility, converts the VoIP packets into atraditional voice call signal, and delivers the signal to the PBX 14.

Calls placed between the PBXs 10 and 14 are transmitted across the VoIPprovider's IP network 24, and potentially over the Internet, as on-netVoIP data transmissions. The VoIP data transmission is part of anInternet Service Provider's (ISP's) information service. The ISP'sinformation service may further provide Internet access to one or morecomputers 50 and 52 at the customer location 12 via the DIA 42, and oneor more computers 54 and 56 at the customer location 16 via the DIA 40.The IAD 26 and the computers 50 and 52 access the DIA 36 via a LAN atthe customer location 12. Similarly, the IAD 30 and the computers 54 and56 access the DIA 40 via a LAN at the customer location 16.

Intra-PBX calls provided in this way have no telco-related charges (e.g.no incumbent local exchange carrier charges or interexchange carriercharges) because the calls never reach a Public Switched TelephoneNetwork (PSTN). For example, the intra-PBX calls provided in this way donot reach a Class 5 central office switch 60 that serves the PBX 10, ora Class 5 central office switch 62 that serves the PBX 14. The Class 5switch 60 may comprise a PRI line card 64 to interface with the PBX 10via a PRI 66. The Class 5 switch 62 may comprise a PRI line card 68 tointerface with the PBX 14 via a PRI 69.

The VoIP service provider has an associated VoIP server office 70 incommunication with the IP network 24. The VoIP server office 70 has aVoIP remote worker feature server 72 on which number ranges for the PBX10, the PBX 14 and the VoIP customer LAN 20 are built and maintained toassist in routing calls. For purposes of illustration and example, thefeature server 72 stores: data elements 74 and 76 for telephone numbers80 and 82, respectively, of the PBX 10; data elements 84 and 86 fortelephone numbers 90 and 92, respectively, of the PBX 14; and dataelements 94 and 96 for telephone numbers 100 and 102, respectively, ofthe VoIP customer LAN 20.

At the customer location 12, a telephone 103 is an end station for thetelephone number 80. At the customer location 16, telephones 105 and 106are end stations for the telephone numbers 90 and 92, respectively. Atthe customer location 22, telephones 107 and 108 are end stations forthe telephone numbers 100 and 102, respectively.

In general, number ranges associated with all foreign PBXs and VoIPprovider-served locations that are to be included in the interworkingarrangement are to be added to and maintained in routing tables of thePBXs. In the example of FIG. 1, the PBX 10 is modified to store thenumber range of the PBX 14 and the number range of the VoIP customer LAN20 in its routing table. Thus, data elements 90′ and 92′ for thetelephone numbers 90 and 92 of the PBX 14, and data elements 100′ and102′ for the telephone numbers 100 and 102 of the VoIP customer LAN 20are added to and stored in the routing table of the PBX 10 withinstructions to route outgoing calls to these numbers to the IAD 26. TheIAD 26 converts the calls into VoIP packets, and communicates the callsto the IP network 24 for processing by the VoIP server office 70.

Similarly, the PBX 14 is modified to store the number range of the PBX10 and the number range of the VoIP customer LAN 20 in its routingtable. Thus, data elements 80″ and 82″ for the telephone numbers 80 and82 of the PBX 10 and data elements 100″ and 102″ for the telephonenumbers 100 and 102 of the VoIP customer LAN 20 are added to and storedin the routing table of the PBX 14 with instructions to route outgoingcalls to these numbers to the IAD 30. The IAD 30 converts the calls intoVoIP packets, and communicates the calls to the IP network 24 forprocessing by the VoIP server office 70.

The VoIP server office 70 comprises a firewall 120 which interfaces theremote worker feature server 72 to the IP network 24. The remote workerfeature server 72 facilitates calls, either incoming to the remoteworker or outgoing from the remote worker, through the IP network 24 totheir intended destinations based on its stored number ranges. The VoIPserver office 70 also includes a media gateway 122 to enable its VoIPserved customers to place calls to the PSTN via an access tandem 124.The media gateway 122 is controlled by a soft switch 126.

For purposes of illustration and example, consider a worker whose homePBX is the PBX 10 at the customer location 12. The worker has assignedto him/her a telephone number of 847-555-0129 that typically resides onthe PBX 10. Consider the worker, who normally works at the customerlocation 12, traveling to the customer location 16 to work for someperiod of time. The remote worker feature enables the worker to receivetelephone service (e.g. receive incoming calls and place outgoing calls)at a remote PBX (e.g. the PBX 14 at the customer location 16) using thesame telephone number (e.g. 847-555-0129).

Methods of providing incoming and outgoing calls to enable the worker touse his/her telephone number of 847-555-0129 at the PBX 14 at thecustomer location 16 are described with reference to FIGS. 2 and 3.

FIG. 2 is a flow chart of an embodiment of a method of providingincoming calls to a remote worker having a particular telephone number.To initiate the remote worker feature, acts indicated by blocks 136, 138and 140 are performed. These acts may be performed in an order thatdiffers from the order depicted in FIG. 2.

As indicated by block 136, an administrator instructs the home PBX toroute all calls for the telephone number to the IAD of the home PBX. Inthe above example, the PBX 10 is instructed to route all calls for847-555-0129 to the LAD 26.

As indicated by block 138, the administrator further instructs the VoIPplatform to route all calls for the telephone number to the remote PBX.In the above example, the remote worker feature server 72 is instructedto route all calls for 847-555-0129 to the PBX 14.

As indicated by block 140, the method comprises building the telephonenumber of the remote worker on the remote PBX. In the above example, thetelephone number 82′ of 847-555-0129 is built on the PBX 14.

As indicated by block 142, an incoming call for the telephone number isinitially received by the home PBX. In the above example, the incomingcall for 847-555-0129 is received by the PBX 10. The incoming call maybe received from the Class 5 switch 60.

As indicated by block 144, the home PBX routes the received call to itsIAD. In the above example, the PBX 10 routes the incoming call for847-555-0129 to the IAD 26.

As indicated by block 146, the IAD of the home PBX converts the call toVoIP and routes the call to the VoIP server office 70. In the aboveexample, the LAD 26 converts the call to a VoIP call, and routes theVoIP call to the VoIP server office 70 via the DIA 36 or alternativeInternet access facility and the IP network 24.

As indicated by block 150, the VoIP server office 70 receives the VoIPcall via the IP network 24. As indicated by block 152, the remote workerfeature server 70 routes the VoIP call to the IAD of the remote PBXbased on the telephone number. In the above example, the remote workerfeature server 70 routes the VoIP call to the IAD 30 of the PBX 14 viathe IP network 24 and the DIA 40.

As indicated by block 154, the VoIP call is received by the IAD at theremote PBX, and is converted back to a conventional call. In the aboveexample, the VoIP call is received by the IAD 30, which converts theVoIP call to a conventional call, and provides the conventional call tothe PBX 14 via the PRI 34.

As indicated by block 156, the remote PBX routes the call to a stationassociated with the telephone number. In the above example, the PBX 14routes the call received from the IAD 30 to a telephone 160 associatedwith the telephone number 847-555-0129 as previously instructed by theadministrator.

FIG. 3 is a flow chart of an embodiment of a method of providingoutgoing calls placed by the remote worker.

As indicated by block 172, an outgoing call is placed from the telephonenumber of the remote worker at the remote PBX. In the above example, theoutgoing call is placed from the telephone 160 associated with thetelephone number 847-555-0129 at the PBX 14.

If the outgoing call is destined to a non-emergency telephone number(e.g. a number other than 9-1-1), then the remote PBX routes theoutgoing call to its IAD as indicated by block 174. In the above examplefor the case of a non-emergency telephone call, the PBX 14 routes theoutgoing call to the IAD 30.

As indicated by block 176, the IAD of the remote PBX converts the callto VoIP and routes the call to the VoIP server office 70. In the aboveexample, the IAD 30 converts the call to a VoIP call, and routes theVoIP call to the VoIP server office 70 via the DIA 40 or alternativeInternet access facility and the IP network 24.

The VoIP server office 70 processes the VoIP call based upon whether theoutgoing call is destined to any of the networked PBX systems or to thePSTN. If the outgoing call is destined to any of the networked PBXsystems, then the remote worker feature server 72 directs the VoIPplatform to route the VoIP call to the IAD of the destination PBX, asindicated by block 180.

If the outgoing call is destined to the PSTN, then the remote workerfeature server 72 directs the VoIP platform to route the VoIP call tothe IAD of the home PBX, as indicated by block 182. As indicated byblock 184, the IAD of the home PBX receives the VoIP call and convertsthe VoIP call back to its conventional form. The home PBX completes thecall destined for the PSTN, as indicated by block 186.

In the above example for the case of a PSTN destination, the remoteworker feature server 72 routes the VoIP call to the IAD 26 of the PBX10 via the DIA 36 or alternative Internet access facility and the IPnetwork 24. The LAD 26 receives and converts the VoIP call back to aconventional call. The PBX 10 completes the call via the Class 5 switch60.

As an alternative to the acts indicated by blocks 182, 184 and 186, theVoIP platform can complete all calls to destinations not served by anyof the customer PBX locations using its own PSTN interface off of theVoIP network. For example, the PSTN calls can be completed by the mediagateway 122 via the access tandem 124.

If the outgoing call is destined to an emergency telephone number (e.g.9-1-1), the remote PBX routes the outgoing call directly to the PSTN forproper routing to a local Public Safety Answering Point (PSAP) 190, asindicated by block 192. The PBX billing number is used as an AutomaticNumber Identification (ANI) number for the outgoing call to allow anemergency service to appropriately respond to the outgoing call. In theabove example for the case of an emergency call, the PBX 14 directs theemergency call to the Class 5 switch 62, which in turn routes the callto the local PSAP 190.

It will be apparent to those skilled in the art that the disclosedembodiments may be modified in numerous ways and may assume manyembodiments other than the preferred forms specifically set out anddescribed herein.

The above disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments which fall within thetrue spirit and scope of the present invention. Thus, to the maximumextent allowed by law, the scope of the present invention is to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

1. A method of routing telephone calls, the method comprising: receivingVoice over Internet Protocol (VoIP) packets at an integrated accessdevice (IAD) from a VoIP remote worker feature server, wherein the IADcommunicates with a first private branch exchange (PBX) located at afirst location; and wherein the VoIP packets are related to a VoIP callintended for a telephone number assigned by a second PBX at a secondlocation.
 2. The method, as recited in claim 1, wherein the IAD convertsthe VoIP packets to analog time-division multiplexed voice data.
 3. Themethod, as recited in claim 2, wherein the IAD sends the analogtime-division multiplexed voice data to an end station associated withthe telephone number via the first PBX.
 4. The method, as recited inclaim 1, wherein the IAD communicates with a dedicated Internet access(DIA) facility via a local area network (LAN) at the first location. 5.The method, as recited in claim 4, wherein the IAD communicates with anInternet Protocol (IP) network via the DIA facility.
 6. The method, asrecited in claim 1, wherein the IAD communicates with the first PBX viaa primary rate interface (PRI).
 7. A system to route telephone calls,the system comprising: a Voice over Internet Protocol (VoIP) remoteworker feature server configured to: receive an instruction from anadministrator to route VoIP calls intended for a telephone number to afirst public branch exchange (PBX), wherein the telephone number isassigned by a second PBX; receive a VoIP call intended for the telephonenumber from a second integrated access device (IAD) communicating withthe second PBX; and route the VoIP call to a first IAD communicatingwith the first PBX.
 8. The system, as recited in claim 7, wherein theVoIP remote worker feature server stores telephone numbers assigned bythe first PBX, telephone numbers assigned by the second PBX, telephonenumbers assigned by a hosted Internet Protocol communication service(HIPCS) local area network (LAN), or any combination thereof.
 9. Thesystem, as recited in claim 8, wherein the VoIP remote worker featureserver communicates with the first PBX, the second PBX, the HIPCS LAN,or any combination thereof via an Internet Protocol (IP) network. 10.The system, as recited in claim 9, wherein the VoIP remote workerfeature server includes a firewall that interfaces the VoIP remoteworker feature server with the IP network.
 11. The system, as recited inclaim 7, wherein the VoIP remote worker feature server receives a secondVoIP call associated with the telephone number from the first IAD. 12.The system, as recited in claim 11, wherein the VoIP remote workerfeature server includes a media gateway.
 13. The system, as recited inclaim 12, wherein the VoIP remote worker feature server routes thesecond VoIP call to a public switched telephone network (PSTN) via themedia gateway, wherein the second VoIP call is intended for adestination accessible via the PSTN.
 14. A method of routing telephonecalls, the method comprising: building a telephone number at a firstpublic branch exchange (PBX), wherein the telephone number is assignedby a second PBX; receiving a call placed to the telephone number at thefirst PBX from a server.
 15. The method, as recited in claim 14, whereinthe telephone number is assigned to a particular individual.
 16. Themethod, as recited in claim 15, wherein the particular individualtravels from a location associated with the second PBX to a locationassociated with the first PBX.
 17. The method, as recited in claim 14,wherein the first PBX stores a plurality of telephone numbers assignedby the second PBX.
 18. The method, as recited in claim 17, wherein thefirst PBX routes telephone calls intended for the plurality of telephonenumbers assigned by the second PBX to an integrated access device (IAD)communicating with the first PBX.
 19. The method, as recited in claim14, wherein the first PBX receives an emergency call from an end stationassociated with the telephone number.
 20. The method, as recited inclaim 19, wherein the first PBX routes the emergency call to a publicswitched telephone network (PSTN) via a switch, wherein an automaticnumber identification (ANI) number associated with the emergency call isa billing number of the first PBX.